1. Field of the Invention
The present invention relates to an information processing apparatus to which nonvolatile storage devices of different types can be connected, and a data processing method executed by the information processing apparatus.
2. Description of the Related Art
In recent years, there has been proposed an apparatus equipped with a function of erasing user data stored in a disk, as a security function. For example, in an image forming apparatus, the function corresponds to a function of erasing original image data, an address book stored or the like by a user, in a batch. Further, recently, an increasing number of apparatuses have come to use a semiconductor storage device called an SSD (solid-state drive) using a flash memory, in place of a magnetic HDD.
In the case of performing full erase on a magnetic HDD which performs magnetic recording, a method is generally used which overwrites an area storing user data with random values a plurality of times so as to reliably erase magnetic traces. For example, an invention disclosed in Japanese Patent Laid-Open Publication No. 2004-153517 has realized an apparatus in which the number of times of erasure can be set according to a desired security level, and erasure is executed according to the set number of times of execution of erasure.
When a semiconductor storage device is employed, information is stored in an on-chip semiconductor, and hence differently from a magnetic HDD from which values on a magnetic substance of a disk can be read by decomposing the same, it is very difficult to read values stored thereon by decomposing the semiconductor storage device.
Recently, however, there is used a semiconductor storage device which performs distributed writing called wear leveling so as to prolong the service life of a flash memory in the storage device. The semiconductor storage device which performs wear leveling executes writing while replacing one block with another so as to preferentially use blocks used fewer times for writing than other blocks. For this reason, information might be left in blocks used before replacement, depending on a block replacement control method for wear leveling.
According to the invention disclosed in Japanese Patent Laid-Open Publication No. 2004-153517, when the security level is set high, erasure is performed a plurality of times irrespective of the type of a disk installed in the device. Therefore, the erasure requires a long time period. On the other hand, in the semiconductor storage device, even if overwriting is simply performed a plurality of times, user data might be left in blocks on the flash memory, depending on the above-mentioned block replacement control method for wear leveling.